Magnetic convergence device for cathode ray tubes

ABSTRACT

A blue lateral control device for color television picture tubes is provided which includes three magnetic members. One of the magnetic members is positioned adjacent to the two other magnetic members which are spaced from each other. All three magnetic members are interconnected so that rotation of one of the magnetic members will result in simultaneous rotation of the other magnetic members. The aforementioned Abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

United States Patent a 111 3,852,693

Schwalm Dec. 3, 1974 [54] MAGNETIC CONVERGENCE DEVICE FOR 3,742,406 6/1973 Erickson 335/2l2 CATHODE RAY TUBES 3,781,731 12/1973 P081 ..313/77 X [76] Inventor: Walter A. Schwalm, 745 Barberry Ln., Lake Forest, lll. 60045 [22] Filed: Dec. 4, 1973 [21] Appl. No.: 421,675

[52] US. Cl. 335/212, 313/77 [51] Int. Cl. H01f 1/00 [58] Field of Search 335/210, 212; 313/75, 76,

[56] References Cited UNITED STATES PATENTS 3,305,744 2/1967 Werst 335/212 X 3,341,729 9/1967 Shari .4 335/212 X 3,605,053 9/1971 Anthony.... 335/212 3,701,065 10/1972 Mirsch 335/212 3,713,057 1/1973 Lostumo 313/77 X Primary ExaminerG. Harris Attorney, Agent, or Firm-George H. Gerstman [57] ABSTRACT A blue lateral control device for color television picture tubes is provided which includes three magnetic members. One of the magnetic members is positioned adjacent to the two other magnetic members which are spaced from each other. All three magnetic members are interconnected so that rotation of one of the magnetic members will result in simultaneous rotation of the other magnetic members.

The aforementioned Abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

14 Claims, 8 Drawing Figures PATENTED 3W .3. 852,683

sum 2 or 2 FIG. 2

FIG. 4

FIG. 7 Av I may be combined with the deflection yoke into a MAGNETIC CONVERGENCE DEVICE FOR CATIIODE RAY TUBES BACKGROUND OF THE INVENTION 7 This invention relates to an improved blue lateral control portion of the convergence system used on color television picture tubes.

In common usage, the convergence system components have become identified as the purity control, blue lateral control and convergence control assemblies. These components are produced separately or in combination with each other. Some or all of them single mechanical unit.

The blue lateral control is so named as it is usually positioned so as to have the greatest effect on the electron stream landing on the blue phosphor spots of the picture tube and deflecting it laterally with respect to the remaining red and green electron streams. It may, however, be positioned so as to have its major effect on any one of the three electron streams with subsequent less effect on the other two streams.

While the greatest deflection is onone electron stream, it may also simultaneously deflect the remaining streams most desirably in the opposite direction. In any case, the control of the electron beams is required so that proper convergence of the electron beams may be ultimately achieved.

Example of the structure and operation of certain prior art blue lateral controls can be found in the US. Pat. to Rennick, No. 3,308,328, the U.S. Pat. to Melone, No. 3,332,046, and the US. Pat.'to Anthony, No. 3,512,023.

One of the problems with the blue lateral controls is that when considerable correction is necessary in a given tube, defocusing of one or-more of the beams results. To reduce this effect it is desirable to move one beam in one direction while moving the remaining beams in the opposite direction. This reduces the maximum amount of field required for correction and hence reduces the. defocusing effect.

One type of blue lateral which has been found to have relatively effective properties is the type wherein the magnetic material is in the form of movable rings, such as exemplified by the US. Pat. toMelone, No. 3,332,046. However, this type of blue lateral is relatively expensive to manufacture. It is thus an object of the present invention to provide a relatively inexpensive blue lateral control-which is simple to manufacture and requires less parts. i

Another object of this invention is to produce a blue lateral device in which a minimum defocusing results from utilization of selected magnetic field patterns.

Some blue laterals use magnetic materials which are easily demagnetized and are somewhat unstable, and hence do not retain their full magnetic property. Thus an object of this invention is to utilize stable magnetic materials.

Another object of this invention is to provide a blue lateral device which can easily be combined with other convergence components and/or the deflection yoke to form a modular unit.-

'Another object of this invention is to provide a blue lateral device which is extremely simple to adjust.

BRIEF DESCRIPTION OF THE INVENTION tioned on the neck of a color television picture tube nearest one electron beam and two additional permanently magnetizable members adapted to be angularly positioned with respect to the first magnetizable member, all in a plane normal to the electron beams. The three magnetizable members are mechanically interconnected in such a way that the rotation of one member simultaneously rotates all three members. A housing adapted for fastening to the neck of the color picture tube contains a bearing means to support the mag netic members and to permit their axes of. rotation at right angles to the electron beams.

The invention covers several possible magnetic patterns suitable for obtaining the desired results. Although the specification describestwo such patterns, persons skilled in the art will be capable of developing a number of additional patterns which may give satisfactory performance. The magnetic patterns described will laterally deflect one of the beams of the color picture tube in one direction while deflecting the remaining two-beams in an opposed direction. In common usage the single beam is normally the one associated with the screen blue phosphor dot landings and the remaining beams are associated with the red and green phosphor dot landings.

In the illustrative embodiment, the particular method of magnetizing the magnetic members chosen will permit displacement of the single beam in one direction while simultaneously displacing the remaining two beams in an opposite direction substantially /2 the distance while keeping the latter two in the same position relative to one another.

In the illustrative embodiment, the magnetic members are generally cylindrical and bevel gears are formed at each of the opposite ends of the first magnetic member. Bevel gears are formed at one end of the second and third magnetic members, and the bevel gears interconnect with each other to form a cooperative gear train. A thumb wheel is connected to the first magnetic member for aiding the operator in turning the first magnetic member. Frictional members are provided toprevent accidental rotation of the magnetic members. 5

A more detailed explanation of the invention is pro vided in the following description and claims, and is illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of the magnetic members forming the blue lateral of the present invention,

FIG. 2 is a perspective view of a magnetic blue lateral control device constructed in accordance with the principles of the present invention;

FIG. 3 is a cross sectional view, taken along the line 33 of FIG. 2;

FIG. 4 is a front view of the second magnetic member used on the device illustrated in FIGS. 2 and 3, partially broken for clarity purposes;

FIG. 5 is a cross section view, taken along the line 55 of FIG. 4; 7

FIG. 6 is a schematic illustration of the bar magnet used in the first magnetic member; and

FIG. 7 is a schematic illustration of a narrower pole bar magnet than the bar magnet of FIG. 6.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT The magnetic blue lateral control device of the present invention is adapted for connection to the neck 10 of a conventional color television picture tube 12, which is a cathode ray tube having electron gun means 14 for developing a green electron beam, a red electron beam and a blue electron beam,

A' first magnetic member 16 is provided in mechani-' cal engagement with a second magnetic member 18 and a third magnetic member 20, which magnetic members 18 and 20 are spaced from each other in diametric opposition. In the illustrative embodiment, magnetic members 16,18 and 20 are generally cylindrical, with the axes of members 18 and 20 being parallel to each other, diametrically opposite, and perpendicular to the axis of magnetic member 16.

As shown in FIG. 1, magnetic member 16 has one pair of poles, while each of magnetic members 18 and 20 have two pairs of poles. First magnetic member 16 controls the blue beam, second magnetic member 18 controls the red beam and third magnetic member 20 controls the green beam.

For optirrium operation to reduce the defocusing effect of the blue lateral control the first magnetic member 16 should have a wide pole which tends to reduce the divergencyof the magnetic field at the point where it intercepts the electron beam. An example of prior art with a narrow-pole and a divergent-field is shown in FIG.'7.

In the illustrativeembodiment,-the magnetic members 16-18 and 20 each comprise plastic tubular holders having magnets inserted therein and having a bevel gear connected to at least one end thereof.

For example, referring to FIG. 4, a second magnetic member 18 (which is identical to third magnetic member 20) is shown therein and includes a tubular holder or housing 24 having magnet 26 located therein. Magnet 26 has two pairs of poles, as indicated in FIG. 1. A gear portion 28 is formed at one end of tube 24, with gear portion 28 having a bevel gear 30 at one end thereof.

Magnetic members 18 and 20 as illustrated in FIG. IA may have one pole on each side. To provide the necessary field for this mode of magnetization it is essential to magnetize member 16 with three poles per side, the center pole of which should be diffused in the manner previously described.

ber 16. First member 16 is similar in construction to second and third members 18 and 20, but the magnet located within the plastic tube forming first member 16 is magnetized differently from the bar magnets'of members 18 and 20, as indicated in FIG. 1. Further, while members 18 and 20 have gears only at one of their ends, first magnetic member 16 has gears at opposite ends thereof to mesh with the gears of the other magnetic members. Additionally, a thumb wheel 36 is connected to member 16 concentrically therewith, so that the operator can turn all three magnetic members 16, 18 and 20 simultaneously by rotating thumb wheel 36.

ently. For example, instead of using plastic housings,

the magnetic members could consist of solid magnetic material. Other equivalent constructions will become apparent to those skilled in the art.

Each of the magnetic-members 16, 18' and 20 are journaled within appropriate bearing means, for support and rotational movement. To this end, a ringshaped' housing 40 is provided for placement upon the neck 10 of cathode ray tube 12. Housing 40 is secured upon neck 10, with a screw inserted through apertures 42and a clamping arrangement is provided by turning the screw forwardly, all as is well-known in the art. Housing 40 is formed of a non-magnetic material, such as plastic, to permit the magnetic members 16, 18 and 20 to operate properly. r

.Housing 40 carries a pair of trunnions 44 and 46 which serve to provide bearing surfaces for cylindrical magnetic members 18 and 20, respectively. Friction clips 48 and 50'are provided to maintain magnetic 'been provided which has relatively few parts, enables simple magnetization and is extremely easy to operate. Although magnetic'members 18 and 20 are shown parallel to eachother and perpendicular to magnetic member. 16, it is to-be understood that other angles may be utilized without departing from the scope of the invention. It is further to be understood that other modifications and substitutions may be made without departing from the novel spirit and scope of the present invention.

What is claimed. is:

1. A magnetic convergence device for a cathode ray tube having electron 'gun means for developing three electron beams, which comprises:

a first magnetic member;

a second magnetic member;

a third magnetic member;

said second and third magnetic members being,

spaced from each other and being coupled to said first magnetic member with the axes of said second and third magnetic members extending angularly with'respect to the axis of said first magnetic member; and

means coupling said first, second and third magnetic rotation of the other two magnetic members about their respective axes.

2. A device as described in claim 1, including a nonmagnetic housing adapted for connection to the neck of a cathode ray tube, said housing including bearing means supporting said magnetic members and permitting them to rotate about their respective axes. I

3. A device as described in claim 1, wherein each of said magnetic members includes a non-magnetic, generally cylindrical container with a bar magnet located with said container.

4. A magnetic device as described in claim 1, wherein said coupling means comprises a gear formed at one end of said second magnetic member, a gear formed at one end of said third magnetic member, and a gear formed at each of the opposed ends of said first magnetic member, said gears being interconnected to form a cooperative gear train.

5. A magnetic convergence as described in claim 4, wherein said gears are beveled.

6. A magnetic convergence as described in claim 1, and including a thumb wheel connected to said first magnetic member, for aiding the operator in turning said first magnetic member to thereby cause simultaneous rotation of the other magnetic members.

7. A magnetic convergence as described in claim 1, wherein each of said magnetic members comprises a generally cylindrical bar magnet.

8. A magnetic convergence as described in claim 1,

wherein said first magnetic member provides a magnetic flux that is relatively diffuse along the length of the magnetic member.

9. A magnetic convergence as described in claim 1, wherein the axes of said second and third magnetic members are generally parallel to each other and are generally perpendicular to the axis of said first mag netic member.

10. In a magnetic convergence device including a housing adapted for connection to the neck of a cathode ray tube having electron gun means for developing three electron beams, the improvement comprising, in combination:

a first magnetic member;

second and third magnetic members;

a pair of gears carried by said first magnetic member;

a gear carried by said second magnetic member and meshed with one of the gears of said first magnetic member;

a gear carried by said third magnetic member and meshed with the other gear of said first magnetic member;

means for rotating one of said magnetic members to thereby simultaneously rotate all three magnetic members; and

bearing means carried by said housing supporting said magnetic members and permitting them to rotate.

11. In a magnetic convergence device as described in claim 10, wherein each of said magnetic members in' cludesa non-magnetic, generally cylindrical container with a bar magnet located within said container.

12. in a magnetic convergence device as described in claim 10, wherein each of said magnetic members comprises a generally cylindrical bar magnet.

13. In a magnetic convergence device as described in claim 10, wherein said first magnetic member provides a magnetic flux that is relatively diffuse along the length of the magnetic member.

14. In a magnetic convergence device as described in claim 10, wherein the axes of said second and third magnetic members are generally parallel to each other and are generally perpendicular to the axis of said first magnetic member. 

1. A magnetic convergence device for a cathode ray tube having electron gun means for developing three electron beams, which comprises: a first magnetic member; a second magnetic member; a third magnetic member; said second and third magnetic members being spaced from each other and being coupled to said first magnetic member with the axes of said second and third magnetic members extending angularly with respect to the axis of said first magnetic member; and means coupling said first, second and third magnetic members, whereby rotation of one of said magnetic members about its axis will result in simultaneous rotation of the other two magnetic members about their respective axes.
 2. A device as described in claim 1, including a non-magnetic housing adapted for connection to the neck of a cathode ray tube, said housing including bearing means supporting said magnetic members and permitting them to rotate about their respective axes.
 3. A device as described in claim 1, wherein each of said magnetic members includes a non-magnetic, generally cylindrical container with a bar magnet located with said container.
 4. A magnetic device as described in claim 1, wherein said coupling means comprises a gear formed at one end of said second magnetic member, a gear formed at one end of said third magnetic member, and a gear formed at each of the opposed ends of said first magnetic member, said gears being interconnected to form a cooperative gear train.
 5. A magnetic convergence as described in claim 4, wherein said gears are beveled.
 6. A magnetic convergence as described in claim 1, and including a thumb wheel connected to said first magnetic member, for aiding the operator in turning said first magnetic member to thereby cause simultaneous rotation of the other magnetic members.
 7. A magnetic convergence as described in claim 1, wherein each of said magnetic members comprises a generally cylindrical bar magnet.
 8. A magnetic convergence as described in claim 1, wherein said first magnetic member provides a magnetic flux that is relatively diffuse along the length of the magnetic member.
 9. A magnetic convergence as described in claim 1, wherein the axes of said second and third magnetic members are generally parallel to each other and are generally perpendicular to the axis of said first magnetic member.
 10. In a magnetic convergence device including a housing adapted for connection to the neck of a cathode ray tube having electron gun means for developing three electron beams, the improvement comprising, in combination: a first magnetic member; second and third magnetic members; a pair of gears carried by said first magnetic member; a gear carried by said second magnetic member and meshed with one of the gears of said first magnetic member; a gear carried by said third magnetic member and meshed With the other gear of said first magnetic member; means for rotating one of said magnetic members to thereby simultaneously rotate all three magnetic members; and bearing means carried by said housing supporting said magnetic members and permitting them to rotate.
 11. In a magnetic convergence device as described in claim 10, wherein each of said magnetic members includes a non-magnetic, generally cylindrical container with a bar magnet located within said container.
 12. In a magnetic convergence device as described in claim 10, wherein each of said magnetic members comprises a generally cylindrical bar magnet.
 13. In a magnetic convergence device as described in claim 10, wherein said first magnetic member provides a magnetic flux that is relatively diffuse along the length of the magnetic member.
 14. In a magnetic convergence device as described in claim 10, wherein the axes of said second and third magnetic members are generally parallel to each other and are generally perpendicular to the axis of said first magnetic member. 